<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
</body>
<script>
  function User(name){
    this.name = name
  }

  User.prototype.show = function(){
    console.log(this.name)
  }

  let tom = new User("tom")
  tom.show();

</script>
</html>